Archive through November 06, 2013

[fcurrier]

Got 3 K321 heads resurfaced. Dropped them off at local Carquest, they sent them to their machine shop in Bangor - 150 miles south - and I picked them up again at local Carquest. $35 each, no shipping involved. Not bad, I thought.

But wait - there's more. There was a $2/head hazerdous waste disposal fee AND a 5.5% SALES TAX charged on the DISPOSAL FEE!

Allen, your video in the Garage is spot on!

 

[dfrisk]

BILL J., Steve S. - If you read the last paragraph of that whole article, it summarizes that TORQUE in the typical operating range of the engine makes the most difference, so my vote is for torque.

Since that article is from Hot Rod everything is biased towards drag racing, which is fine. But really had next to nothing to do with Bill's situation. The K301 is governed to 3600 RPM, and with no load can run that RPM with a very little throttle opening, probably only about 8-10% of it's fully opened air/fuel flow rating. Once he drove into the tall grass the governor opened up the throttle to try to hold 3600 RPM till the throttle was fully opeened but the engine wasn't able to produce enough TORQUE to hold that engine speed, so slowed to 3200 RPM where it made more TORQUE and tractor speed slowed so the mower pulled less hard. That's called Torque RISE. It's measured as a percentage of increase over full load torque when an engine is producing maximum HP at full throttle. And MORE is always better.

The one thing I hope everybody that takes the time to read that article takes away from it is also towards the end of the article, think next to last paragraph. "EVERRYTHING in an engine is a TRADE-OFF", a compromise to increasing "performance under the curve" as opposed to making BIG HP or torque numbers at a single point on a chart. The operation of an engine is totally dynamic, RPM, and therefore HP & torque being produced is constantly changing in relation to the loads the engine is exposed to and expected to pull.

BILL - The fact your K301 pulled down under 3600 RPM means you over-loaded the engine, the load required more than 12 HP. But the fact that the engine only pulled down to 3200 RPM, not to it's torque peak which IIRC is around 2400-2500 RPM, you still didn't exceed it's maximum potential power, or ability to do Work. Once you pull an engine down below it's torque peak RPM the RPM's drop off fast!

Anyhow, I have to ask.... How did you know what RPM's your K301 was running? Or was this just a hypothetical situation?

 

[dfrisk]

FRANK - WOW.... I had a K241 bored .010"+ O/S, crankshaft throw ground .010" U/S, valves ground & lapped, head planed flat, the whole engine "hot-tanked" (cleaned), and I think the bill was $130 incl. tx.

Same prices I paid 8 yrs ago on my K321, but the Kohler parts prices were WAY higher, so I put a Stens piston, gaskets (except head gasket) and stellite exh valve in, but used a Kohler rod.

Your east coast auto parts stores must have marble floors!

 

[bjamison]

Dennis F & everyone - good info on torque vs hp.

Some background. Over the years, I've worked off info, as everyone does, that is passed on and down. Sometimes this info works - but no one really knows why and sometimes when you dig in the details, you find the info is a crock. Whatever was working - was something else. Sometimes info is repeated so much that folks take it as fact - and I am guilty of this many times too.

So I've always been told that one runs these single cylinder Kohler engines full throttle, 3600 rpms, max torque is around 3400/3200 rpms, so when you hit a patch of tall grass, heavy bit of snow or a hard piece of sod when plowing, the engine pulls down (typically) to 32-3400 rpms - to the max torque, right where you want it. Absent any torque curve info vs hp, it all made sense to me. I plow the 126 into a tall patch of grass, the rpms drop, the engine grunts, the job gets done as advertised - right? So I was challenged on this and started digging.

My first discovery was that the Kohler max torque is around 2500ish rpms - not 32/3400 rpms. So that when you hit the tall patch of grass and the engine pulls down to max torque is rubbish.

Second thing I considered (as was pointed out earler on this thread) is that when you are tooling along mowing normal grass or just doing some light work, you ain't burning a lot of fuel, you might be making 3600 rpms, but not putting out full hp to do so. With that, as the engine starts to loose rpms under load, the governor starts to kick-in to maintain rpms by boosting gas to the engine and dynamically pushing the engine to it's hp limit vs the load. Dennis - as you said, once the governor has done all it can do, the rpms drop as the engine is overwhelmed - but continues to do the work at hand.

So in the end - what I've been told about hp and torque and what I thought was correct, was incorrect.

None of this torque vs hp really matters in the end - I guess, but I find interesting to figure out.

But I come to this site in part because of the expertise that the members bring along. IMHO, the knowledge base on this forum far exceeds any other I participate on - much thanks!

BTW - my engine rpm values were estimates, not measured.

Bottom line is - I know more now than I did yesterday and if the grass get's to tall I either need to mow it more often or get an IHCC with more hp to get the job done or something....

 

[sshaff]

I agree more torque produces more horsepower, (which is a rate that work gets done) so the two are related in that sense. There are differences, however, between torque and work:
http://wiki.answers.com/Q/What_are_the_differences_between_torque_and_work

 

[dfrisk]

BILL torque peak varies my engine model. I think the K241 was as low as 2200 RPM, K321 was 2600 to 2800. The rest were from 2400 to 2600. There's been a Kohler torque chart posted here several times in the past. And the torque curves show how it builds and then drops off giving the torque rise when the engine pulls down from 3600.

If you'd have spent as many days plowing/disking, etc with Super M-TA's & 450's, etc with the Torque-Amplifier as I have you'd be able to print a torque curve just by running a tractor for an hour. Those old gas 4-cyl IH engines were rated at 1450 RPM and the T/A reduced speed by 33%, but IH advertised they increased pull power by 45% because they got the engine back on top of the HP curve when shifted to the low side. So you watched the tach till it wiggled down around 1000 RPM and then pulled the T/A back. And normally you ran full load RPM the rest of the way up the hill. Soon as you felt & heard the engine tone change when it wasn't making full power you let the lever fly worward again. The SM-TA wouldn't do it, but the 450 would reward each movement of the T/A by pulling the frt wheels off the ground up to a foot.

There was a big articulated 4WD JD I ran quite a bit that would have needed about a 3-4 stage T/A to run properly. It's FL RPM was 2100 and if the tach wasn't reading at least 1500-1600 when I dropped the chisel plow in the ground within a second it would be lugging well down below 1000. It was NOT a fun tractor to run.

 

[mschutz]

Frank C, That 122 looks salvageable and I am willing to bet it will look perfect by spring. I got a call this week to go look at two Cub Cadets or they will go to scrap. I hate to hear that! Just what I need, more tractors.

 

[mschutz]

My two cents on hydro vs gear drive. I have both and I like the one I am driving at the time the best.

 

[fcurrier]

Melody: Trust me, it's parts! (But some good ones). Steering spindles are frozen solid, tunnel cover/dash tower had been cut off and bolted back on, 1 rear rim is toast, but that's OK because they're both inside-the-rim valve stems. No PTO clutch. The old girl IS worn out! However, I can salvage the engine and wanted one to rebuild this winter, anyway and I walked into the deal with eyes wide open and met a very nice guy in the process. Parts aren't getting any cheaper and shipping costs keep rising, so I can't resist any that are reasonably available. A 125 is next on my list to get serious about, before snow interferes with my plans. Once word gets around that you're interested in Yellow/White, strange things can come your way! I know the "Like I Need Another Tractor" feeling, but something (Greed?) always overrides it!

 

[fcurrier]

My pics aren't as pretty as Kraig's:

 

[sblunier]

And the numbers extracted from a post way back in 1998....

Harry Bursell - 02:21am Jul 26, 1998 EST (#934 of 935)
Tom @923 and others - I found a Kohler K series graph chart in a book by Paul Dempsey which shows:
K301(12hp) peak torque 22.25ft lbs @2200 rpm. Also max. brake hp is 12 @35-3600rpm but torque is 17.5ft lbs. at this point.
Others interested are:
K241(10hp) peak torque 16.5ft lbs @2400rpm, and max. brake hp is 10 @3600rpm torque is 14.5ft lbs.
K321(14hp) peak torque is 23.5ft lbs @2400rpm and max. brake hp is 14 @3600rpm torque is 20.5ft lbs.
The BIG K341(16hp) peak torque is 28.25ft lbs. @2600rpm with max. brake hp 16 @3500rpm torque is 23.5ft. lbs.

 

[sblunier]

Twin cylinder ratings (from 82 series literature)

Briggs 656CC/40cuin 16hp boxer twin:
RPM @ max power = 3350
Peak torque = 25.8 lbft

Kohler KT17-I 42.18 cuin 17hp boxer twin:
RPM @ max power = 3400
Peak torque = 26.4 lbft

Onan 47.7cuin 19hp boxer twin:
RPM @ max power = 3200
Peak torque = 30.86 lbft

Kohler M18 42.18 cuin 18hp boxer twin:
No info found - similar to KT17

Kohler M20 46.98 cuin 20hp boxer twin:
No info found.

Kubota specs.

Kubota D600B 600cc/36.61 cuin 16.5hp 3 cylinger liquid cooled diesel:
RPM @ max power = 2600
Peak torque = 25.5 lbft

Kubota WG600B 600cc/36.61 cuin 21hp 3 cylinger liquid cooled gas:
RPM @ max power = 2800
Peak torque = 30.5 lbft

All ratings are based on 3800 no load and 3600 governed speed.

 

[bwittman]

Steve,

Am I reading this correctly in that A K-301 has more torque at about 2/3 - 3/4 throttle than it does at full throttle?

I'm just a dumb old truck driver, and don't really understand the true difference between torque and horsepower. I always thought that horsepower drove accessories, but torque twisted off drive shafts.

 

[sblunier]

My thoughts on torque and HP.

HP is nice, and it is a nice comparative number for assessing engine capabilities.....BUT in tractor applications with governed engines, the peak torque generated when the engine is pulled down is what gets the real work done!!! This "torque rise" over rated speed torque gives the engine it's lugging ability and is the real measure of the work it can produce. Denny did a really nice job explaining this concept below. (And after some time on a big IH with a TA, the "butt dyno" knows exactly when to grab "the stick" to keep the engine pulling well!!)

Real world Cub Cadet applications:

Mowing: IMHO, mowing is not a "high torque" job. Very few of us will lug a Kohler down to it's peak torque when mowing. Think about it, we may get it to bark a little in heavy grass....but have you really ever pulled a mower deck so hard that you "got under" the torque curve and almost killed it???? Most of us back out of the hydro or ride the clutch way before this happens, and then select a slower speed so as not to sacrifice cut quality.......SOOOOOO, IMHO, mowing is not a high torque application 99% of the time.

Snow Blowing: This application to 100% about TORQUE!!! Single stage throwers work best when run full, and most of us push them hard to get them to that point. Knocking 600 rpm or more off of the rated speed is common place, and often times more....usually to the point that we occasionally "get under it" and almost kill the engine. This is peak torque and max work at it's finest!!!!

Plowing: In a gear drive this is a 50/50 proposition, light to medium load in lighter areas, and pulling way down into the peak torque in others (what we wouldn't give for a TA on a gear drive Cub!). The fixed gear ratio makes the gear drive unit a slave to the plow draft. In a hydro Cub plowing is a high torque application (especially if you are running down Deere's!!). The hydro allows you to load in up and pull it down to where you are really maximizing your work potential and utilizing the available engine torque. Most slush box operators are not content to loaf along and pick up the pace until the engine is really working and lugged down, "getting under it" enough times to know exactly where "the line" is and then riding the line......To paraphrase Wyatt or Travis (can't remember)from an early Plow Day: "Ride'r till it bucks, back off just a little...then go give'r hell"

All of the other Cub Cadet chores fall somewhere between these categories.

In short, if you must maintain high engine RPM to do a satisfactory job (like mowing) you can thank the HP portion of the curve for your engine for it's efforts. Conversely, if the job requires (or allows) you to pull it down into the peak torque band, then that "torque rise" bubble in the curve is making it happen for you.

As Denny and others pointed out below, everything is a trade off, you can't have fuel efficiency (who cares right?) and high torque rise at the same time. Engines designed to run high RPM's and scream, typically won't lug well.....it's all about compromise.

One of the best attributes of our beloved machines is IH's engine choices.....as the data below shows, the K Series and boxer twins are torque monsters when pulled down, giving them capabilities well beyond their "HP Rating"....this cannot always be said for the newer "HP race" engines.

 

[sblunier]

Brian,

The K-301 makes peak torque when the load pulls the engine down to 2/3-3/4 rated speed.....On a governed engine, the throttle plate is typically wide open at this point, maximizing the fuel delivery in an attempt to regain lost RPM's, but the load has exceeded the "rated speed load" and the engine begins to sacrifice RPM. Eventually continuing to add load will exceed the engine's ability to produce torque and you "get under it" ...then it falls on it's face and dies.

The thing to remember is that on a governed engine, even if you set the hand throttle to a no load speed less than 3600rpm, the throttle plate will still go wide open (thanks to the governor's actions) when the load increases. So if your hand throttle is set at or above the peak torque rpm of your engine model, it should be capable of delivering peak torque because the governor will constantly open the throttle to match the load applied to the engine, eventually opening it wide open (max fuel delivery).

 

[dfrisk]

To add to Steve's description, and to enlighten many here, there are two types of engine governors. Most medium & heavy truck engines, especially diesel's have maximum speed governors. They only restrict the engines maximum speed under light loads, otherwise they do nothing to restrict or control engine speed. The gas pedal controls engine speed and power up to the point the engine is running at maximum speed. Their purpose is basically to prevent engine damage from over-speeding.

Second type of governor, like our CC's and ALL full-size farm tractors have is a Constant Speed governor. The governor is controlled by the throttle lever on the dash, and the governor controls the throttle blade in the carb or the injection pump rack in a diesel engine to maintain that RPM setting under changing load conditions. If you're pulling a steep hill mowing.. or plowing, or whatever, the gov. increases throttle opening or inj. pump setting. If you're going down a hill the gov. closes the throttle opening or reduces the injection pump setting.

Just because you have the throttle set to run 3600 RPM has NOTHING to do with whether you're making rated HP with your engine. You have the POTENTIAL to make full rated HP if it's needed. Like Steve said about mowing, most of us mow only using a fraction of available HP... all except Bill J. of course. As long as you can increase the throttle pposition and the engine can accelerate, you're not creating max HP yet.

 

[sblunier]

Good point Denny!

Actually, just about everything these days is "rev limited".....because the electronics in our cars and trucks will kill the ignition at or very near "red line" RPM. I'm sure you've heard somebody say "I pushed it right up to the rev limiter" and one time or another....either very lead footed drivers or on a TV car show.

BUT, as Denny pointed out, a rev limiter is not a constant speed governor......

 

[bjamison]

Dennis F & Steve B - there is another type of speed limiter IH used. I had one on my 1970 IH Scout 800A with 196 cu-in 4 cylinder. If you found yourself going at or above 45 mph on a back/two lane road, in a curve and hit a pot hole, the front end would automatically go into a death wobble and the driver would automatically want/make the Scout slow down so you could live another day and mow tall grass with the IHCC...

 

[thoffman]

Bill J,
Good 'un!

 

[dfrisk]

BILL - NONE of the IH trucks I ever drove would run fast enough to get "Death Wobble".

And that's not an "IH Thing", I lurk at the Dodge Turbo-diesel site, can't post since I stopped suscribing to their magazine, but the 4 WD Dodge p/u's do it too. I've put close to a half MILLION Miles on Ford Twin-Traction Beam frt suspension trucks and never had any problems like that. In fact, on my current truck, I only rotate the tires when the REAR tires show more wear than the frts. It only has 301,500 miles on it.